1. Technical Field
The present invention relates generally to scalable decoders, and more specifically relates to a system and method of improving decoding quality by analyzing the statistical properties of the enhancement layer information from the current and reference frames.
2. Related Art
As the popularity of systems utilizing compressed data standards, such as MPEG, H.26×, etc., continues to grow, the ability to efficiently process and communicate compressed data remains an ongoing challenge. One of the challenges of transmitting compressed video involves the sensitivity to network impairments. Because compressed video uses predictive coding algorithms and variable-length coding, transmission channel problems can result in error propagation or “drift.” In particular, motion compensation, which is widely used, allows the error to propagate both temporally and spatially. Because of this, new techniques are required that limit the extent of error propagation.
In recent years, the development of scalable video encoders has focused on eliminating the drift by providing systems in which the base layer (BL) is predicted only from base layer. This strategy has been taken one step further in the development of MPEG-4 Fine Granularity Scalability (FGS) systems, in which the enhancement layer (EL) is also predicted only from BL. However, while recent scalable video coding algorithms are becoming more efficient at compressing the video, they lose compression efficiency because they ignore all EL information when predicting the BL.
The coding efficiency can be increased by optimally combining the quantizer information of the BL and EL by modeling the evolution of DCT coefficients during the encoding process. While this approach improves the rate-distortion performance of the overall coder, it is also prone to drift in variable bandwidth channels, since the EL packets can be dropped irregularly depending on the traffic conditions.
Furthermore, previous attempts to improve the drift-free scalable video coder require significant modifications to the encoder structure. Such modifications are not always feasible for improving the existing drift-free scalable video codec, such as MPEG-4 Fine Granular Scalability (FGS).